As an example of a transmission apparatus for a tractor of the above-noted type, there is one described in Patent Document 1. In the apparatus described in Patent Document 1, a traveling transmission section is comprised of a speed changing outputting section receiving the output from the planetary transmission section and a forward/reverse switchover device receiving the output from the speed changing output section.
More particularly, in the case of the apparatus described in Patent Document 1, the speed changing output section includes a first speed clutch, a second speed clutch, a third speed clutch and a fourth speed clutch. In association with a speed changing control by the hydraulic stepless speed changing section, the first speed clutch, the second speed clutch, the third speed clutch and the fourth speed clutch are controlled to be appropriately switched over into an engaged state or a disengaged state, whereby the output from the planetary transmission section is transmitted via the forward/reverse switchover device to the traveling transmission device in one of the four speeds including the first to fourth speed ranges and with also being speed-changed in a stepless manner in each speed range. The forward/reverse switchover device includes a forward clutch and a reverse clutch. In operation, when the forward clutch is switched into the engaged state, the output from the speed changing output section is converted into a forward drive force and then transmitted as such to the traveling device. When the reverse clutch is switched into the engaged state, the output from the speed changing output section is converted into a reverse drive force and then transmitted as such to the traveling device.